Encapsulated gas or partial vacuum CT contrast material

Abstract

The present invention provides an encapsulated gas or partial vacuum particle contrast media for use in CT imaging. In an exemplary embodiment, the invention provides an enteric contrast medium formulation. An exemplary formulation comprises, (a) an enteric contrast medium comprising a encapsulated gas or partial vacuum particle suspended in water. Exemplary encapsulated gas or partial vacuum particle has a specific gravity between 0.2 and 1.5. In various embodiments, the encapsulated gas or partial vacuum particle is suspended in aqueous media by an agent compatible with enteric administration of the formulation to a subject in need of such administration. In an exemplary embodiment, the contrast material is incorporated into a pharmaceutically acceptable carrier in which the material is suspended homogeneously. In an exemplary embodiment, the encapsulated gas or partial vacuum particle comprises 5% or more of the weight of the contrast material formulation. The invention also provides methods for imaging of the abdomen by dual energy CT or spectral CT contemporaneously with the delivery of the encapsulated gas or partial vacuum particle contrast material into the bowel lumen with or without the deliver of a second complementary contrast material into the blood vessels or other body compartments. The invention also provides methods for the digital separation of CT signal produced by the contrast media of the invention from the CT signal produced by other contrast media or bodily tissues to generate multiple resultant CT images with the contrast medium of the invention subtracted or highlighted.

What is claimed is: 
     
       1. A method of acquiring contrast enhanced X-ray or computed tomography or dual energy computed tomography or spectral computed tomography or photon counting computed tomography projection data of a subject, the method comprising:
 orally administering to the subject a diagnostically effective amount of an enteric contrast medium formulation comprising a stable aqueous suspension of from 10% (wt/wt) to 50% (wt/wt) hollow borosilicate microspheres encapsulating gas or partial vacuum suspended in water containing 0.2% to 0.5% xanthan gum as a suspending agent maintaining the microspheres in suspension, the formulation having a viscosity of from 50 g/cm-sec to 2400 g/cm sec; and
 acquiring the projection data of the subject. 
 
 
     
     
       2. The method according to  claim 1 , wherein the X-ray or computed tomography or dual energy computed tomography or spectral computed tomography projection data is reconstructed into an image of the abdomen of the subject, where the computed tomography image is used to distinguish the enteric contrast medium formulation from other materials in the abdomen of the subject. 
     
     
       3. The method according to  claim 1 , wherein the X-ray or computed tomography or dual energy computed tomography or spectral computed tomography projection data are used for 2-material, 3-material, or multi-material decomposition and reconstructed into the image. 
     
     
       4. The method according to  claim 1 , wherein the method further comprises administering to the subject a second contrast medium different from the enteric contrast medium, and the second contrast medium is administered through a route selected from oral administration, intrathecal administration, intravesicular administration, enteric administration, anal administration, intracatheter administration, intra-device administration, intravascular administration, administration into a fistula, and administration into a surgically created pouch. 
     
     
       5. The method according to  claim 4 , wherein the enteric contrast medium and the second contrast medium are distinguishable from each other in the image based on x-ray attenuation (CT number) at single energy spectrum CT; or wherein the enteric contrast medium and the second contrast medium are distinguishable from each other in the image based on their CT number, relative X-ray attenuation at different X-ray spectra, or both. 
     
     
       6. The method according to  claim 4  wherein the enteric contrast medium has CT number of less than about 50 Hounsfield Units in the image or less than about −50 Hounsfield Units in the image or greater than about 100 Hounsfield Units in the image. 
     
     
       7. The method according to  claim 4  wherein the enteric contrast medium has an 80:140 kVp CT number ratio of greater than about 2.1 in the image or less than about 0.8 or less than zero in the image. 
     
     
       8. The method according to  claim 4 , wherein the second contrast medium is a member selected from an iodinated contrast medium, a Ba-, Gd-W-, Bi-, Mg-, Yb- and a Ta-based contrast medium and a silicon based contrast medium. 
     
     
       9. A method of acquiring contrast enhanced dual energy computed tomography or spectral computed tomography or photon counting computed tomography projection data of the abdomen of a subject, said the method comprising:
 orally administering to said the subject a diagnostically effective amount of an enteric contrast medium formulation comprising: of  claim 8  a stable aqueous suspension of from 10% (wt/wt) to 50% (wt/wt) hollow borosilicate microspheres encapsulating gas or partial vacuum suspended in water containing 0.2 to 0.5% xanthan gum as a suspending agent maintaining the microspheres in suspension, the formulation having a viscosity of from 50 g/cm-sec to 2400 g/cm-sec; and 
 acquiring said the projection data of said the subject's abdomen. 
 
     
     
       10. The method according to  claim 9 , wherein the enteric contrast agent distributes in the gastrointestinal tract of the subject and does not decrease the density of the contents of the gastrointestinal tract. 
     
     
       11. The method according to  claim 9 , wherein the enteric contrast agent in the intestinal tract of the subject has 80:140 kVp CT number ratio of 0.9 or less, or 1.8 or higher. 
     
     
       12. The method according to  claim 9 , wherein the enteric contrast agent wherein the small bowel transit time of the enteric contrast agent is less than 12 hours in a normal subject.